Uncircumcised men are at a much greater risk of becoming infected with HIV from heterosexual sex than circumcised men, say researchers.

They found a man who is circumcised is up to eight times less likely than one who is not to acquire HIV from "straight" sex.

A team from Australia have analysed data from more than 40 studies.

Circumcising males seems highly desirable

Researchers from University of Melbourne Royal Women's Hospital

They found evidence that the HIV virus targets specific cells from the inner surface of the foreskin.

These cells possess HIV receptors, making this area particularly susceptible to infection.

The researchers suggest that male circumcision provides significant protection against HIV infection by removing most of the receptors.

Circumcision also reduces the likelihood of contracting other sexually transmitted diseases, such as gonorrhoea and syphilis, which make a person more vulnerable to HIV infection.

The most dramatic evidence of this protective effect comes from a new study of couples in Uganda, where each woman was HIV positive and her male partner was not.

Over a period of 30 months, no new infections occurred among 50 circumcised men, whereas 40 of 137 uncircumcised men became infected - even though all couples were given advice about preventing infection and free condoms were available to them.

Cultural problems

In many countries circumcision is frowned upon for cultural or religious reasons.

However, the scientists, led by Professor Roger Short, from the University of Melbourne Royal Women's Hospital, wrote in the British Medical Journal: "In light of the evidence presented here, circumcising males seems highly desirable, especially in countries with a high prevalence of HIV infection."

Alternatively, say the authors, the development of 'chemical condoms' - products which can block HIV receptors in the penis and the vagina - might provide a more acceptable form of HIV prevention in the future.

A spokesman for the National Aids Trust said the findings were not so relevant in the West, where the vast majority of HIV transmission was between gay men.

In Africa, heterosexual infection was far more prevalent, and world-wide about 70% of HIV positive men acquired the virus through vaginal sex.

Safe sex education

He said: "We know from the US example, where the majority of men already are circumcised, that circumcision does not protect against infection from anal intercourse.

"We really have to look at safe sex education and condom use as the way forward here."

The HIV charity The Terrence Higgins Trust (THT) called for further research.

Jack Summerside, THT health promotion officer, said: "While it seems from this research that circumcised men may be less likely to become infected with HIV through vaginal intercourse, using condoms still remains the best protection against HIV and other sexually transmitted
infections."